1. Field of the Invention
The present invention relates to techniques of printing input data from an external apparatus by performing a form overlay process.
2. Related Background Art
There is a printer of the type that can make various formatted sheets or the like by printing page data, which is different at each page, on a form page of form data, as illustrated in FIG. 15. This function is called xe2x80x9cform overlayxe2x80x9d. More precisely, a plurality set of form data are stored in advance in a printer. Upon a form overlay instruction of page data, designated form data is printed together with page data as many pages as instructed. The form data is developed into a bit map image at each page, and similarly the page data is developed into a bit map image. The two types of image data is ORed to write a synthesized bit map image into a memory and converted into image signals used for printing.
Since the form data is developed into a bit map image at each page, the print process takes a long time and the throughput is lowered. In order to shorten a print process time, in another type of a printer, form data is registered in the form of intermediate codes easy to be converted into a bit map image.
In still another type of a printer, form data converted into bit map images are stored in advance to shorten the print process time.
In order to deal with various types of print styles, such as two-page print (FIG. 10) and enlargement/reduction print, it is necessary to change each form through rotation, reduction or the like. Therefore, form data of intermediate codes stored in advance cannot be used directly.
If bit map images converted from form data are stored in advance, a very large memory capacity becomes necessary particularly in the case of a laser printer or the like having a high resolution. The cost becomes therefore high.
It is necessary for a page printer to store an output image of one page in a bit map memory. In order to store an output image, a full paint system and a banding system have been used. In the former system, a full-page bit map is required, and in the latter system, an output image of one page is generated by a memory (band memory) having a capacity of several fractions of one page.
With the full paint system, a bit map memory of one page is used, and print data is converted into a bit map image in the bit map memory and transferred to a printer mechanism. This system requires a large capacity of a bit map memory, for example, about 8 MB for A3 sheet at a resolution of 600 dpi. However, since an output image of one page is always generated even for a large amount of data or data requiring a long image generation time, the print-out of input data is reliable.
With the banding system, a memory having a capacity of several fractions of one page is cyclically used to form an image in units of band. In this case, print data of one page is stored in the form of intermediate codes, and a fractional bit map memory is used as a ring buffer to control the generation and transfer of an output image synchronously with the print mechanism. As compared with the full paint system, the print operation can be performed with a smaller memory capacity, and at a high speed because of parallel execution of the generation of an output image and the transfer thereof to the printing mechanism.
In order to print the same data on each page of, for example, formatted sheets by the above-described two printing systems, a form overlay function has been incorporated. With this function, formatted sheet data is stored as form data in a printer in advance, and numerical data (called back member data) to be printed in a frame of each formatted sheet is later transferred to synthesize it with the form data.
With conventional form overlay, form data transferred from a host computer is stored in a storage area of a printer in a page description language (PDL) type. Thereafter, back matter data is supplied and analyzed. Upon detection of a completion event (e.g., form feed command) of the analysis, the already stored PDL form data is read to generate intermediate codes. The form data and back matter data are synthesized in the bit map memory to generate an output image (called an event drive macro scheme).
With this scheme, form data of each page is analyzed to generate intermediate codes so that the process time becomes long.
Although the same form data is often used for several pages, it is used as a counterpart of the back member data to generate intermediate codes. Therefore, the intermediate codes of each page cannot be shared with another page. The storage area of the intermediate codes therefore becomes large.
With a conventional form overlay function of another type, form data (PDL data) transferred from a host computer is converted into intermediate code data and stored in a storage area of a printer. Intermediate codes generated from back matter data and the intermediate form data read from the storage area are synthesized on a bit map memory to generate an output image (called an intermediate scheme).
With this conventional intermediate scheme, the storage area of the intermediate form data generated in the printer becomes larger than that the form data is stored in the form of PDL.
Also with the conventional intermediate scheme, since the memory capacity of form data can be known only after it is analyzed in the printer and converted into intermediate codes, the memory capacity in the printer cannot be managed, for example, by a host computer. Therefore, a memory over-capacity or the like may occur and the form data cannot be registered normally.
The conventional intermediate scheme processes an input image so as to make it easy to generate a rasterized image (for example, scalable fonts are stored after they are converted into a bit map image of a predetermined size). Therefore, if the already registered form data is enlarged or reduced, the image quality and process speed are lowered.
A printer capable of printing data on an A3 sheet, an A4 sheet can be printed either in the lateral direction or elevational direction. With the conventional intermediate code scheme, however, an input image is rotated in order to make it easy to generate a rasterized image so that the form data both in the lateral and elevational directions are required to be stored and the memory capacity increases.
In the case of a printer which can change an output resolution and is used with the conventional intermediate code scheme, since an input image is processed to make it easy to generate a rasterized image, it becomes necessary to store form data sets as many as the number of output resolutions and the memory capacity increases.
As above, with the conventional intermediate code scheme, it is necessary to prepare intermediate codes satisfying all the conditions of printing back matter data so that the memory capacity increases.
The invention has been made in consideration of the above problems and aims to provide an image processing apparatus and method capable of performing a form overlay process at high speed.
According to an embodiment of the present invention, there is provided a print control apparatus capable of communicating with a data generator source via a predetermined communication medium, comprising: first registration means for registering first print data of a first data format generated by the data generator source into a memory; second registration means for converting the first print data into second print data of a second data format and registering the second print data in the memory, the second print data being most suitable for outputting from a printing unit; data processing means for developing, in an overlay manner on the memory, print data of each page sequentially sent from the data generator source and the second print data stored in the memory to generate a print image; and control means for controlling an overlay print of the printing unit in accordance with the print image.
According to another embodiment of the present invention, there is provided a print control apparatus for receiving print data, generating image data from the print data, and outputting the image data to a printer, comprising: storage means for storing at least one set of form data; output means responsive to a presence of form data designation in the print data for reading the image data of the designated form data from a cache memory, synthesizing the read image data with the image data generated from the print data, and outputting a synthesized image data to the printer; cache means for registering the generated image data to the cache memory.